Return a NULL histogram pointer on construction error

base/metrics/histogram_base.h

Index: base/metrics/histogram_base.h
diff --git a/base/metrics/histogram_base.h b/base/metrics/histogram_base.h
index 4248bd84a4c3136f6f2a1ee60483fa54e14ce2e9..bb563123abd2a71617bf603786739f9841094f57 100644
--- a/base/metrics/histogram_base.h
+++ b/base/metrics/histogram_base.h
@@ -79,6 +79,11 @@ class BASE_EXPORT HistogramBase {
     NEVER_EXCEEDED_VALUE = 0x10
   };
 
+  enum ConstructionBehavior {
+    kDoNotAllowBadConstruction = 0,
+    kAllowBadConstruction = 1
+  };
+
   explicit HistogramBase(const std::string& name);
   virtual ~HistogramBase();